Electric heater



E. N BROWN AND M. H. SHOENBERG.

ELECTRIC HEATER.

APPLICATION FILED OCT- 2, I919. RENEWED OCT. 18,1921.

Patented N OX. 22, 1921.

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meme HEATER. A'PPLICATION FILED OCT 2, I9I 9 RENEWED OCT. 18,1921.

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APPLICATION FILED OCT, 2, i919. RENE-WED OCT-18,1921.

l,398,2 1 7. Patented Nov. 22, 1921.

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EDMUND N. BROWN A D-MIL ON n. SHOENBERG,' OF sA FRANCISCO, CALIFORNIA, VASSIGNORS To MAJESTIC ELECTRIC DEVELOP MENT COMPANY, OF SAN FRAN- orsoo, CALIFORNIA, A CORPORATION OF CAL FORNIA.

ELECTBI IC HEATER.

To all whom it may concern:

Be it'known that we, EDMUND N. BROWN and MILTON H. SHOENBERG, citizens of'the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented certain new and useful Improvements in Electric Heaters, of which the following is a-s-pecification.

Our invention relates to electric heaters ofthe reflector type and having reflecting surfaces of parabolic contour, with the heating element centered about the focus of the reflecting surface so that the heat rays Wlll surface of revolutlon generated by revolv ing' one parabolic curve and its inner portion cooperating with a surface of revolution generated by the revolution of another parabolic curve. I

Our invention will be understood from the following description in connection withthe accompanying drawings in which Figure 1 is a vertical sectional View of an electric heater embodying our invention; Fig. 2 is a cross-sectional view on the line 22 of Fig. 1; Fig. 3 is an enlarged sectional view on the line 33 of Fig. 1; Fig. 4 is an enlarged fragmentary view of the hinge joint in the standard or support; Fig. 5, is a front elevation of the reflector; Fig. 6 is an enlarged fragmentary view, partly in section, of the heating element or unit shown in Fig. 5; Fig. 7 is a diagrammatic view of the heating coils or resistance wire in the heating element of Fig. 5; Fig. 8 is a cross section on the line 88 of Fig. 6; Fig. 9 1s a diagrammatic view showing the relation of the curvature of the different parts of the reflector; Fig. 10 illustrates different cross sectional shapes which may be employed in the mufiles ofthe heating units;

1 Fig. 11 is a plan View of another form. of

heating unit; Fig. 12 is across-sectional view onthe line 1212 of Fig. 11; 1g. 13 1s a tion I) 0 6, formed by Specification of Letters Patent. Patgnted N 22 1921 Application filed October 2, 1919, Serial No. 327,880. Renewed October 18, 1921.

Serial N 508,611.

plan view of one of the halves of another form of heating. unit; Fig. 14 is a cross sectional view on the line 141& of Fig. 13; Fig. 15 is a fragmentary vertical sectional view of a modified form of our heater; and

Fig. 16 is a fragmentary view showing the overlapping ends of the retaining band attached to the outer ends of the guard wires.

.The reflector comprises an outer portion A, formed as, a surface of revolution by revolving aparabolic arc ab, about the axis c -d, see Fig. 9; and an inner concave porrevolving a parabolic arc to, about the axis 0-03, the reflector being thus formed of two parabolic surfaces of revolution and may be said to constitute a compound parabolic surface.

The heating unit 5, is of annular or ring form and is so located that its outer peripheral portion 5* is centered about the focus of the outer parabolic surface, while its inner peripheral portion 5 is centered about the ocus of the inner parabolic surface, the rays from any point cooperating with the opposite or far side of the concave surface, as interminals, so that the current will traverse the two halves in parallel.

The muffle may be of various cross-sectional shapes, as indicated in Fig. 10.

In Figs. 11 and 12, we have shown a tubular. mufile constructed of two circular semicylinders 14, 14', which inclose the resistance coil and are secured together by bolts or rivets 15, apertures 16 being provided to permit the escape of the heat and the radiation from the coils. The interior walls of the muflfle may be grooved or fluted to receive the convolutions of the resistance wire and keep them separated.

In Figs. 13 and 14, the inner surfaces of the two mating muflie sections Z7, 17' are provided with a spiral groove in which 'housed the resistance wire, which may be coiled'or spirally wound to' provide a great length of heating surface if desired. [The entire muffle 17 becomes highly heated and radiatesheat from its surface. I

' We have devised'terminal connectors and supports for the heating unit which are" nector '23. Mica washers and 26 are 23. A metal sleeve 28 slides with. a tight.

clamped against the inner and outer sides of the reflector A to insulate the connector. 7 The terminals of the resistance heater wire 12 pass through the standards 20 and are clamped by screws 27 within the connectors fit over the outer endof the connector 23,

which is split to provide a yieldingplug which presses outwardly against the inner walls of the sleeve. The end ofthe cord conductor 30 is clamped and electrically connected to the sleeve by a screw 31. outer sleeve 32 of porcelain or other insulating material, slides tightly over the metal sleeve and forms a protecting insulating.

sheath. In the arrangement shown in Fig. 1, the terminal connectors project through the outer back cover, while in Fig. 15', the

connectors are inclosed by the cover and the insulated conductors 30,30pass through an aperture 33 in the cover plate;

The outer margin of the reflector is bent or shaped into an annular channel form at 36, and fits into an "angle'recess formed in the cover plate and may be secured in place by screws 37 or in any other suitable manner. The outer cover or back member lO,

consists of sheet metal of concavo-convex shape, spaced from the reflector to .provide a heat insulation. angular margin fitting about-the rim ofthe reflector. as shown in Fig. 15, or maybe proi'ided with a marginal flange 41, having a. channel shape rim 42, as in Fig. 1.

The wire guard or cage 45, has a spring metal marginal band 47', having separated ends 47*, 47 which overlap when the band' is contracted for the purpose of inserting within the channel groove 36 o 42. the inner end 42? being formed into aneye or knob to facilitate removal. as shown in Fig. 16.

WVhile we have illustrated the reflector herein described in connection with heaters mounted on a pedestal. it will be understood It may terminate'in an that the reflector may be used in heaters of .other types such as grates and logs. It will ii also be evident to engineers that various outer surrounding portion being a surface a heating element substantially centered about the focus of said outer portion.

2. A heater, comprising a reflector of concave form, the central portion being a surface of revolution of one curvature and the of revolution of' a different curvature, andouter surrounding portion being a surface of revolution of .a' diflerent' curvature, and an annular heating element substantially centered about the foci of. the, inner and the outer portions. a 3. A heater, comprisin a reflector of concave form having centra and outer portions being surfaces of revolution generated by curves of different curvature and each substantially parabolic in section, and an annular heating element. substantially centered about the foci of said inner and outer portionsa 4. A heater, comprising a reflector of concave form having central and outer portions being surfaces of revolution generated by curves of different curvature-and each sub stantial'ly parabolic in section, and an annular heating element substantially, centered about the foci of said inner and outerport-1ons and supported over the junction of the two curved portions.

5. A heater, comprising a reflector of concave form having central and outer portions of different curvature, each being a surface of revolution formed by the rotation of a section of a parabola, said parabola sections being of different curvature and an annular heating element centered substantially-about the foci of said parabolic surfaces so that the heat rays fromthe outer lower portion of the heating element will be reflected by the outer reflecting portion and the heat rays from the inner lower' portion of said element willbe reflected from the central reflecting portion and both said reflected heat rays being projected outwardly in substantially parallel lines.

6. A heater as set forth in claim 1, and

an outer casing or back member spaced from the reflector and having an annular marginal portionprovided with an annular re-' from the reflector and having an annular marginal portion provided ,with an annular recess forming a seat to receive the rim of having complementary sections adapted to the reflector, said marginal portion being support'a resistance Wire-and maintain its formed with a channel shaped rim, and a parts in the desired configuration or shape 10 Wire guard or cage having a marginal band In testimony whereof We afiix our signa- 5 adapted to seat in said channel shaped rim. tures.

8. A heating element for electric heaters, v EDMUND N. BROWN. comprising an annular refractory muflie MILTON H. SHOENBERG. 

